ANATOMY AND HISTOLOGY-CLASSIFICATION. SpOUg. 5 
consist of elongated rhombohedrons of calcite, with their optic axes simi¬ 
larly oriented through the entire spicule (and therefore not radially 
arranged with respect to the axial fibre). They have a sp. gr. of 2‘62 ; 
refractive indexes, E. = T485, W. = T65. 
0. Schmidt (35) admits the presence of tetractine spicules in Caminus 
vulcani , 0. S., and traces a reduction in their numbers relative to the 
monaxon spicules through Caminus osculosus , Grube [= Pacliymatisma 
johnstoni , Bk.— Rec.]. and C. vulcani , 0. S., up to complete disappear¬ 
ance in C. apiarum , 0. S. 
Ontogeny. 
Goette (7), on the subject of the development of the gemmules and 
young sponge of Spong'dlci lacustris , contrasts the results obtained by 
Marshall and himself. 
Phylogeny. 
Schulze (36), in discussing the affinities of the Sponges, states that no 
other naturalist besides Kent has seen collared cells in the free-swimming 
sponge larva ; and he suggests that Kent has mistaken for larvse rolled- 
up portions-of the flagellated endoderm of the adult Sponge. Schultze 
also points out that P rotospongia hcecheli of Kent differs fundamentally 
in histological structure from a true Sponge. Its structureless matrix 
differs from gelatinous connective tissue in the absence of fixed connective 
tissue corpuscles ; and it is not invested with a pavement epithelium, as 
is the connective jelly in Sponges. Moreover, the flagellated cells are 
immersed in it up to the collar, and not merely seated on it, as in Sponges. 
Schulze also argues against the views of Biitschli and Marshall, and con¬ 
cludes that the Cnidaria and Sponges are nearly related, that their 
divergence did not commence before the stage of ciliated larvae, but how 
much later there is nothing at present to show. 
Marshall (25) criticizes the opposing views of Schulze and Sollas, and 
endeavours to show that Sponges are degraded Ccelenterata. 
Classification. 
Lendenfeld (12, 19) gives the following classification of the Cal- 
carea :— 
Older, Calcispongi^:. Suborder 1 , Homoccela ; suborder 2, Hete- 
PvOC(ELA. 
Homoccela. 
Earn. 1. Asconidce. (Genera, Ascetta , Ascaltis , Ascandra .) 
Fam. 2. Homodermiclce , new ; Homoccela with radial tubes. (Genus, 
Homoderma , new.) 
Fam. 3. Leucopsiclce , new ; Homoccela with abundant mesoderm, in 
which mouthless ascon persons are imbedded ; with a large 
pseudogaster and pseudostome. (Genus, Leucopsis , new.) 
